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Foundations Updated 2026-09 View as Markdown

Pointer Arithmetics

You previously learned what is a pointer and how to manipulate pointers. In this tutorial you will be learning the arithmetic operations on pointers.

You previously learned what is a pointer and how to manipulate pointers. In this tutorial you will be learning the arithmetic operations on pointers. There are multiple arithmetic operations that can be applied on C pointers: ++, –, -, +

Incrementing a Pointer with (++)#

Just like any variable the ++ operation increases the value of that variable. In our case here the variable is a pointer hence when we increase its value we are increasing the address in the memory that pointer points to. Let’s combine this operation with an array in our example:

c
#include <stdio.h>

int main()
{
    int intarray[5] = {10,20,30,40,50};
    
    int i;
    for(i = 0; i < 5; i++)
        printf("intarray[%d] has value %d - and address @ %x\n", i, intarray[i], &intarray[i]);
    
    
    int *intpointer = &intarray[3]; //point to the 4th element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 4th element
    
    intpointer++; //now increase the pointer's address so it points to the 5th elemnt in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 5th element
    
    return 0;
}

Decreasing a Pointer with (–)#

Just like in our previous example we increased the pointer’s pointed-to address by one using the ++ operator, we can decrease the address pointed-to by one using the decrement operator (–).

c
#include <stdio.h>

int main()
{
    int intarray[5] = {10,20,30,40,50};
    
    int i;
    for(i = 0; i < 5; i++)
        printf("intarray[%d] has value %d - and address @ %x\n", i, intarray[i], &intarray[i]);
    
    
    int *intpointer = &intarray[4]; //point to the 5th element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 5th element
    
    intpointer--; //now decrease the point's address so it points to the 4th element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 4th element
    
    return 0;
}

Adding Pointers with (+)#

We previously increased a pointer’s pointed-to address by one. We can also increase it by an integer value such:

c
#include <stdio.h>

int main()
{
    int intarray[5] = {10,20,30,40,50};
    
    int i;
    for(i = 0; i < 5; i++)
        printf("intarray[%d] has value: %d - and address @ %x\n", i, intarray[i], &intarray[i]);
    
    
    int *intpointer = &intarray[1]; //point to the 2nd element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 2nd element
    
    intpointer += 2; //now shift by two the point's address so it points to the 4th element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the addres of the 4th element
    
    return 0;
}

Note how in the output the address shifted by 8 steps in the memory. You might be wondering why? The answer is simple: Because our pointer is an int-pointer and the size of an int variable is 4 bytes the memory is shift-able by 4 blocks. In our code we shifted by 2 (added +2) to the initial address so that makes them 2 x 4 byte = 8.

Subtracting Pointers with (-)#

Similarly we can subtract:

c
#include <stdio.h>

int main()
{
    int intarray[5] = {10,20,30,40,50};
    
    int i;
    for(i = 0; i < 5; i++)
        printf("intarray[%d] has value: %d - and address @ %x\n", i, intarray[i], &intarray[i]);
    
    
    int *intpointer = &intarray[4]; //point to the 5th element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 5th element
    
    intpointer -= 2; //now shift by two the point's address so it points to the 3rd element in the array
    printf("address: %x - has value %d\n", intpointer, *intpointer); //print the address of the 3rd element
    
    return 0;
}

again the address is shifted by blocks of 4bytes (in case of int).

Other Operations#

There are more operations such as comparison >,

Exercise

Try it

run this one locally 




Expected output
Matched!
Matched!
Matched!






  


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